Add a stat to the smoothness benchmark for avg number of missing tiles.

cc/layer_tree_host_impl.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYER_TREE_HOST_IMPL_H_
 #define CC_LAYER_TREE_HOST_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
@@ skipping 359 matching lines @@
 
     // List of visible layers for the most recently prepared frame. Used for
     // rendering and input event hit testing.
     LayerList m_renderSurfaceLayerList;
 
     PinchZoomViewport m_pinchZoomViewport;
 
     scoped_ptr<FrameRateCounter> m_fpsCounter;
     scoped_ptr<DebugRectHistory> m_debugRectHistory;
 
-    size_t m_numImplThreadScrolls;
-    size_t m_numMainThreadScrolls;
+    int64 m_numImplThreadScrolls;
+    int64 m_numMainThreadScrolls;
 
-    size_t m_cumulativeNumLayersDrawn;
+    int64 m_cumulativeNumLayersDrawn;
+
+    int64 m_cumulativeNumMissingTiles;

[nduca, 2012/12/07 01:14:37]

any reason using the word missingTiles vs numCheckerboards?

 
     DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYER_TREE_HOST_IMPL_H_